I"m mixing a song my son and I put together. My son did the vocal. I did the usual trick of duplicating his vocal track, shifting one track ahead 20ms and the other back 20ms. One channel was panned full left, the other full right. Nothing new.
 
I noticed though that the vocal was predomintally on the left speaker. I checked everything and all looked like it should. I then shifted the two signals so they were both lined up. Now the vocal was centered. I shifted the orignal back 20ms and the copy ahead 20ms. The vocal was now mostly on the right speaker.
 
Anybody have an explanation for this phenomena? Does the brain hear the first track and ignore essentially what is an echo? Sorry if this has been discussed before and I did Google it and could not find anything.
 
Walt

WallyG
 
Anybody have an explanation for this phenomena? Does the brain hear the first track and ignore essentially what is an echo? Sorry if this has been discussed before and I did Google it and could not find anything.
 

To some extent, yes. This is called the Haas Effect or the Precedence effect.

As it goes, I think the thing you're calling "the usual trick" is somewhat incomplete. There's a technique - which I personally don't care for - for thickening a vocal where you what you describe, but you also pitch shift the vocals panned to the side by a few cents, one up, the other down.
 
This creates (supposedly) enough difference between the two sides to create a sense of width. When the two sides aren't different enough, there's no sense of width. You have mono, effectively. And the precedence effect brought about by the delay means it will skew to one side.
 

I always hated the doubling trick.. cheeeeeezey   

Well.. everything in its place. It can be cool sometimes. But I find it to be a bit unsubtle. Better as a deliberate special effect, than a general thing, I think.

Singing a second part is going to be more effective, but also, try this. Arguably it's still cheesy, BUT at least it's a fine bleu de bresse instead of Velveeta.

I'm with Craig on this. Get your son to record a second track and then pan the 2.
 
I've always underwhelmed by any sort of fake doubling techniques. But make sure he sings it as close to the original as possible and watch the timing!! (More important than pitch in my estimation)

The guy's above have given you enough information but I would also want to ask is the track you shifted forward the right channel track. If so this would make sense as the vocal from the left channel will hit you ear 20 ms before the right channel and therefore sound a little louder, As Craig has said, actually performing a doubled track is way more effective than any doubling on a mono source.

40 ms difference between the copies sounds  much to me. Anyway, I never hard pan the vocals, I prefer the Lennon-method. The result sounds more natural to me, which suits the style of songs I make.

Try making a third unaffected copy of the vocal up the middle.